The present invention relates to a propulsion system for a vehicle. It has particular utility in the propulsion and/or positioning of space vehicles.
The majority of propulsion systems in use today rely either on exerting forces against the surface over which they travel (e.g. cars, trains, funiculars (via their supporting rope) etc.), accelerating material which comprises the medium through which they travel in a direction opposite to the direction in which they are being propelled (e.g. propeller aircraft, power driven or manually propelled boats), taking advantage of thermally or gravitationally derived energy gradients (e.g. sailing boats, gliders or surf boards) or ejecting material in the form of fuel carried by the vehicle, either in part as in the case of a jet engine or totally as in the case of a rocket engine. Hitherto, there has been no alternative but to employ the latter method in order to propel or position a vehicle in space.
A problem associated with propulsion systems utilising the latter method is that the volatile fuel required to be carried by the vehicle represents a danger to any crew in the vehicle, the vehicle itself and its contents.
Another problem associated with such propulsion systems is that the range and manoeuverability of the vehicle is limited by the amount of fuel carried.
Yet another problem associated with such systems is that once the vehicle is accelerated, it can only be decelerated by expending further fuel.
The invention may also have utility in specialised terrestrial applications. For example, much effort has been expended in attempting to quieten the propulsion systems of boats. By obviating the need for propellers or such like, the system according to the present invention may provide quieter propulsion than has hitherto been possible.
The principles underlying the present invention will now be explained with reference to and as illustrated in FIGS. 1-9 of the accompanying drawings in which:
One method of moving a space vehicle a short distance is illustrated in FIG. 1. A device (D) inside the vehicle is arranged to project or move an object (W), of significant mass in relation to the mass of the remainder of the vehicle from one end of the vehicle to a receptacle (B) at the other end. It is known that if the object (W) is so projected to the right in FIG. 1, the vehicle will move a distance to the left (to the position S) in FIG. 1. After that movement, the object (W) and the receptacle (B) are at the positions W' and B' respectively. The distance moved will approach the length of the vehicle if the mass of the object (W) is relatively large in comparison to the mass of the vehicle, or will approach zero if the mass of the object (W) is insignificant in comparison to the mass of the vehicle. In any case, the effect will be that the centre of mass of the vehicle and object will not move. For this reason, it is thought that such an activity is of little or no use in propelling a vehicle, since it is assumed that, in returning the object (W), the vehicle will necessarily undergo an equal and opposite displacement to that which it underwent when the mass was originally moved from one end of the vehicle to the other.
Another method of moving a vehicle a short distance is schematically illustrated in FIG. 2. FIG. 2 shows a vehicle (1), on which is mounted a base plate (2), which in turn carries a pivot (O). An arm OA of length R is mounted with one end on pivot (O) and the opposite end carries an object (W) of mass M.
If a force were to be applied to the object (W) with the intention of moving its mass M around the semi-circular arc ACB at speed v, it might be thought that the sum of the centrifugal force acting on the pivot (O) during that motion would have components only in the direction Y and therefore that the vehicle would be moved in the direction Y. However, this is not the case because the force needed to give the initial momentum Mv to the object W will always cancel the component of the centrifugal force. In fact, the application of the initial force to the object (W) will result in an equal and opposite force being applied to the vehicle (1) so that the object (W) and the vehicle (1) would rotate in opposite senses about the pivot (O).
The rotary part of this reaction can be neutralized by arranging for a second identical object (W1) arranged as a mirror image of the first object (W) to rotate in the opposite direction as shown in FIG. 3.
Referring to FIG. 3, if the two objects (W1, W2) are of large mass compared to the mass of the vehicle, then it will be seen that as they begin to move around their semi-circular paths they will exert a relatively large centrifugal force (initially towards the right in FIG. 3) on the vehicle (1) which will in turn will be accelerated to a relatively high velocity by this force owing to its relatively low inertia. As the two objects (W1, W2) approach the point B (having passed points C and E), they will then exert similarly large centrifugal forces to the left in FIG. 3 decelerating the vehicle until it returns to the condition it had when the objects (W1, W2) were launched. Hence it will be seen that the motion of the objects (W1, W2) will be accompanied by an associated movement of the vehicle a distance D1 to the right as shown in FIG. 4. The vehicle moves from positions A to E in that Figure.
If, however, the objects (W1, W2) have a relatively low mass compared to the mass of the vehicle then they will exert a relatively small centrifugal force on the vehicle which will only be accelerated to a relatively low velocity owing to its relatively large inertia. When the masses then approach the point B (having passed points C and E), they will exert similarly low centrifugal forces on the vehicle in order to return it to its initial condition. Therefore, it will be seen that if the masses are relatively small (and hence the centrifugal force is less than in the previous paragraph), the vehicle will have moved a smaller distance D2 to the right. The motion of the vehicle in this case is illustrated in FIG. 5. It will be seen that the reduction of centrifugal force results in the vehicle moving a smaller distance. The vehicle moves from position A to position E in that Figure.
Consideration of the above two paragraphs and FIGS. 4 and 5, will show that the larger the relative mass of the objects (W1, W2) to the mass of the vehicle, the larger the displacement of the vehicle will be. If, for example, the vehicle were to be of negligible mass when compared to the sum of the masses of the objects (W1, W2), then the vehicle would move a distance 2R to the right in FIG. 3. If the vehicle were to have a mass equal to the sum of the masses of the objects (W1, W2), then the effect of the centrifugal force would be to move the vehicle a distance R to the right in FIG. 3.
It will be seen that, in each of the above examples, the centre of mass of the combined vehicle and object system remains in the same position.
As stated above, the fact that the centre of the mass of the combined system is not moved in each of the above examples means that such a method cannot be used to move a vehicle a distance greater than its own length.
However, if the centrifugal force exerted by the masses of the objects (W1, W2) as they travelled from position A to position B were to be reduced below the level seen in the examples above for that mass then the vehicle would be moved over a smaller distance. In other words, in a supposed first movement (in which centrifugal force is reduced), the vehicle would move a first (relatively short) distance in a direction opposite to the direction of movement of the masses.
Then, if the objects (W1, W2) were to be subsequently returned, in a second movement in which the centrifugal force was equal to that seen in the above examples, the vehicle would move a second (relatively long) distance in the opposite direction to the first movement. Clearly, after both the first and second movements had taken place the position of the objects (W1, W2) relative to the vehicle would be unchanged. Moreover, it will be seen that the combination of the first and second movements would result in a net movement of the vehicle and its contents in the direction opposite to said first movement. Hence, it will be seen how, if a way could be found of reducing the centrifugal force exerted by the objects (W1, W2) moving from one end of the vehicle to the other that the centre of mass of the combined system could be moved across space, that mass could thereby be transferred, and that the vehicle could be propelled through space.
It is well known that when a spinning gyroscope is mounted on a pivoted radius arm, so that the pivot is remote from the centre of the wheel forming the spinning mass of the gyroscope, and the gyroscope is subjected to a torque at right angles to the spin axis of the wheel (for instance by means of transfer through the radius arm) then the gyroscope precesses, that is rotates, about a precession-axis that is at right angles both to the spin-axis of the wheel and the applied torque provided that it is free to do so.
FIG. 6 shows a plan view of a spinning wheel, all of whose mass may be considered to be concentrated in its rim of negligible thickness and of radius r. The wheel is connected to a pivot (O) (which forms the centre of precession) by a light rod of length R. A torque T is applied to the wheel in the direction shown.
The mechanism of precession may better be understood by considering the highest and lowest points of the rim of the spinning wheel as illustrated in FIGS. 7A and 7B.
From FIGS. 7A and 7B, the application of the torque T may be considered as tantamount to the application of a force F1 to the top point of the spinning wheel and a force F2 to the bottom point of the spinning wheel, deflecting them and causing a change in the direction of their velocities from v to v' as shown. Thus both velocity vectors are deflected clockwise. It will be realized that an object whose velocity is constantly changing in a direction at right angles to its current velocity moves in a circle.
By conventional two-dimensional mechanics, a non-precessing mass moving in a circle only does so if it is subjected to a constantly applied force defined as the `centripetal` force.
The present inventors realised that by applying oppositely directed forces, (the effect of a torque,) to particles that are themselves, moving in opposite directions as a result of being part of the rim of a spinning wheel they could cause the spinning rim to circle about O without requiring a centripetal force.
It is known that a convenient means (for demonstration purposes) of applying a constant torque to a gyroscope is to offset the gyroscope on a shaft, which is supported at the end remote from the gyroscope by a joint, that allows the shaft to move both laterally and up and down, and to allow the weight of the gyroscope, together with the reaction force at the joint, to be the forces that apply the torque.
It is also known that when the wheel is spun up, suspended and released in this manner the gyroscope will precess at a rate .OMEGA. derived from the equation: ##EQU1## Where: T--MgR--torque at right angles to shaft
M--mass of the wheel PA1 g--acceleration due to gravity PA1 R--length of the shaft PA1 I--moment of inertia of wheel PA1 .omega.--angular spin velocity of wheel PA1 wherein in the precession-dominated portion, the mass of the gyroscope means moves in said first direction and an associated first movement of the vehicle in substantially the opposite direction to said first direction occurs, and, in the translation-dominated portion, the mass of the gyroscope means moves with an associated second movement of the mass of the vehicle in substantially said first direction, wherein said second movement is greater than said first movement and hence the vehicle moves in said first direction. PA1 at least one gyroscope means adapted for precessional motion about an axis remote from the centre of said gyroscope means; means for causing the gyroscope means to follow a path which involves at least one precession-dominated portion and at least one translation-dominated portion, PA1 wherein in the precession-dominated portion, the mass of the gyroscope means moves in said first direction with an associated first movement of the vehicle in substantially the opposite direction to said first direction, and, in the translation-dominated portion, the mass of the gyroscope means is moved with an associated second movement of the vehicle in substantially said first direction; and PA1 wherein said second movement is greater than said first movement and hence the vehicle moves in said first direction.
Further, it will precess about any point in the precessional plane so long as it is launched with initial conditions such that it finds itself travelling at the linear tangential velocity R..OMEGA. where .OMEGA. is determined from equation (1) inserting the value for the torque that so obtains.
With reference to FIG. 8, the present inventors realised that if two gyroscopes of identical mass M and spinning at the same speed .omega., but in opposite directions to one another, were mounted on equal rods with their remote ends pivoted in a frame (0,0') of negligible weight which was itself unrestrained, and were launched in an arc from A to B by whatever means (P), be it a spring, motor, ramp or chemical reaction, in such a way that, at the moment they found themselves being acted on by gravity supplying the torque, their launch velocity was exactly R..OMEGA. where: ##EQU2## then the resulting motion (in the event of the gyroscopes being `perfect` (see below)), would not involve a centrifugal force being exerted on the frame (0,0'), that the frame would not therefore be deflected and that the centre of mass of the system would move a total distance of 2R.
It will be appreciated that if the wheels were not spinning and were then just `dead` masses and were given the same treatment (as far as that is possible given that they would then have NO TENDENCY to move of their own volition when subjected to a torque and would therefore have to be projected with considerable velocity to achieve a similar result), then the frame (0,0') would, (as explained with reference to FIG. 3), be deflected from a distance R from one side of the wheels to a distance R on the other side. The centre of mass of the system would not move.
The present inventors have conducted experiments which show that when a gyroscope is caused to precess by a torque whatever additional angular momentum it acquires combines with the angular momentum already in the spinning mass and if the axis about which it is caused to precess is remote from the centre of the wheel, that an additional linear momentum proportional to the linear tangential velocity of the total moving mass of the gyroscope about that said axis of precession is the only extra dynamic requirement. The experiments conducted further show that, once the gyroscope has been launched on its path of precession about a remote axis as described, the forces exerted by the gyroscope at that axis are largely those involved with application of torque to the gyroscope. Such forces that pass through the axis normal to the tangent at any point in the precessional path of the gyroscope are less than those calculated from the conventional formulae for derivation of centrifugal force of a non-precessing mass. Thus it follows that, provided it is correctly launched, the centre of mass of a gyroscope may be moved around a circle of precession from the one end of a diameter to the other without the full corresponding net force at the centre of precession.
The present inventors further realised that if the mass of the gyroscope could be transferred predominantly by a precession of the gyroscope without a substantial movement in the vehicle, (i.e. providing the first movement referred to above) and thereafter the mass of the gyroscope were to be returned to its original position in relation to the vehicle by means not involving precession (deriving the momentum for that movement from the remainder of the system) (i.e. providing the larger second movement referred to above), then the vehicle would be moved and if this cycle were to be repeated the vehicle would be propelled.
It is arranged that in the precessional motion of FIG. 8, the gyroscopes derive their momentum from each other.
According to a first aspect of the present invention there is provided a method of moving a vehicle in a first direction, which method comprises the steps of : connecting at least one gyrocope means to said vehicle; causing said gyroscope means to follow a path which involves at least one precession-dominated portion and at least one translation-dominated portion,
According to a second aspect of the present invention there is provided an apparatus for propelling a vehicle in a first direction, which apparatus comprises:
Furthermore, the present inventors have conducted experiments which show that if the mass of the wheel of the gyroscope is not concentrated at an infinitely thin rim then an amount of centripetal force is developed which is required to constrain all parts to a circle, or precess, about the same centre 0. However, these experiments have verified that the centripetal force is still less than that predicted by the conventional formula for non-precessing masses.
The practical situation that would thereby be obtained is illustrated in FIG. 9. The gyroscopes would, as a result of their not being `perfect`, exert some centripetal force on the frame (0,0'). The frame would be moved a distance to the right as shown in that Figure, so that by the time the frame (0,0'), had moved from S to T, the gyroscopes have moved to Q and Q' respectively. However, when the gyroscopes are subsequently returned to the right hand side of the frame, the frame will be displaced by a distance 2R to the left in FIG. 9. Therefore, the combined result of the precessional motion and the translational motion would be to move the frame from position S to position U, i.e. over a distance less than the distance 2R obtained in the perfect case of FIG. 8 but nevertheless with a resulting movement in the centre of mass of the system that would not be achieved with `dead` masses.
Advantageously then, a high proportion of the mass of the gyroscope means lies in a plane at right angles to the spin axis of said gyroscope means and is located at a predetermined distance from said spin axis of the gyroscope.
Other experiments have shown that the greater the wheel spin velocity .omega. is in relation to the precessional velocity .OMEGA., the less centripetal force is developed. .OMEGA. and .omega. are related to the applied torque T and the moment of inertia I of the wheel by equation (1).
Preferably, the ratio of the angular velocity of the gyroscope means about its spin axis to the angular velocity of said precession is maximised.
In the absence of a gravitational field the torque to cause the gyroscope to precess in the first place has to be provided. This may conveniently be obtained from an identical gyroscope spinning in the opposite direction and with the same angular velocity as the gyroscope against which it is to be reacted so that the torque being applied to one gyroscope is equal and opposite to the torque on the other gyroscope, the net torque on the vehicle is nil and the two gyroscopes then precess in the same direction, as a pair, about a centre.
Preferably therefore, the apparatus comprises at least first and second gyroscope means such that the torque required for the precession of the first gyroscope means is provided by the second gyroscope means.
In order for this first pair of gyroscopes to precess about a centre remote from the centre of the gyroscopes, they must, as previously stated, be given a linear momentum proportional to their prospective linear tangential velocity when subjected to the applied torque. In a preferred embodiment of the invention this linear momentum may conveniently be derived from an identical pair of gyroscopes with identical attributes arranged as a mirror image of the first pair. In this arrangement the linear momentum required to launch each pair of gyroscopes on their precessional paths are equal and opposite and cancel out so that the net momentum outside the system is nil. Similarly when the two pairs of gyroscopes reach their diametrically opposite point the linear momentum, delivered when the torques are removed, are again equal and opposite and again cancel out leaving no net momentum outside the system.
Preferably then the apparatus comprises at least first and second gyroscope means such that the linear momentum required by said first gyroscope means in order to precess about an axis remote from its centre is derived from the second gyroscope means precessing in the opposite sense.
Advantageously, the apparatus comprises at least first and second pairs of gyroscope means, the torques required by each gyroscope means being provided by the other of said pair, and each pair providing the linear momentumrequired by the other pair.
Preferably, the path of the gyroscope means is such that the motion of the gyroscope means varies continuously between a substantially entirely precessional motion and a substantially entirely translational motion, thereby providing a smooth propulsion to the system.
A smoother propulsion can also be obtained by providing a plurality of groups of gyroscope means and arranging each group to impart said second movement the vehicle at a different time.
Some embodiments of the present invention utilise a gyroscope means which comprises a wheel which is driven by a central hub. A problem associated with such embodiments is that the degree of propulsion that can be provided by the apparatus is limited by the strength of the materials making up the hub itself.
Preferably therefore, said gyroscope means comprises a substantially annular rim which is driven by a means in contact with that rim.
Furthermore, the rim is preferably rotatably supported at a plurality of points around the rim. This has the further advantage that the level of propulsion that can be provided by the apparatus is increased in accordance with the number of means rotatably supporting the rim.
In a preferred embodiment of the present invention, the gyroscope means comprises two counter-rotating annuli which are retained in a frame means. This has the advantage that the torques exerted by each rim substantially cancel one another and that substantially no net torque is exerted by the frame on the vehicle.
The invention will now be described further, with reference to and as illustrated in FIGS. 10 to 28 of the accompanying drawings in which: